TPS92690EVM

TPS92690EVM Boost Evaluation Module User's Guide Literature Number: SLVU803 December 2012 Contents A ........................... 4 .................................................................................................................. 4 Detailed Description ............................................................................................................ 5 2.1 Description ................................................................................................................... 5 2.1.1 Typical Applications ................................................................................................ 5 2.1.2 Features ............................................................................................................. 5 Electrical Performance Specifications ................................................................................... 7 Schematic .......................................................................................................................... 8 Performance Data and Typical Characteristic Curves .............................................................. 9 5.1 Efficiency ..................................................................................................................... 9 5.2 Line Regulation .............................................................................................................. 9 5.3 Switch Node Voltage and LED Current Ripple ........................................................................ 10 5.4 PWM Dimming ............................................................................................................. 10 5.5 Start-up and Shut-down Response ..................................................................................... 11 5.6 Thermal Performance ..................................................................................................... 12 TPS92690EVM PCB layout .................................................................................................. 13 Bill of Materials ................................................................................................................. 14 2 Contents 1 N-Channel Controller for Dimmable LED Drives with Low-Side Current Sense 1.1 2 3 4 5 6 Introduction SLVU803 – December 2012 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated www.ti.com List of Figures ................................................................................................ 4-1. TPS92690EVM Schematic 5-1. Efficiency ..................................................................................................................... 9 5-2. Line Regulation .............................................................................................................. 9 5-3. Switching and LED Current .............................................................................................. 10 5-4. PWM Dimming, fPWM = 200 Hz, Duty Cycle = 50% .................................................................... 10 5-5. PWM Dimming, fPWM = 200 Hz, Duty Cycle = 5% 5-6. PWM Dimming, fPWM = 200 Hz, Duty Cycle = 95% .................................................................... 11 5-7. Start-up Waveform ........................................................................................................ 11 5-8. Shut-down Waveform ..................................................................................................... 11 5-9. Top Thermal Performance 5-10. 6-1. 6-2. ..................................................................... ............................................................................................... Bottom Thermal Performance ........................................................................................... Top Layer and Top Overlay (Top View) ................................................................................ Bottom Layer and Bottom Overlay (Bottom View) .................................................................... 8 10 12 12 13 13 List of Tables ................................................................ 3-1. TPS92690EVM Electrical Performance Specifications A-1. The TPS92690EVM Components List (According to the Schematic Shown in Figure 4-1) ..................... 14 SLVU803 – December 2012 Submit Documentation Feedback List of Figures Copyright © 2012, Texas Instruments Incorporated 7 3 Chapter 1 SLVU803 – December 2012 N-Channel Controller for Dimmable LED Drives with Low-Side Current Sense 1.1 Introduction The TPS92690EVM evaluation module (EVM) helps designers evaluate the operation and performance of the TPS92690 DC-DC N-channel MOSFET controller. The TPS92690 is designed to drive high-brightness light emitting diodes (LEDs) and features a wide input voltage range (4.5 V to 75 V), analog current adjust, PWM dimming, low-power shutdown, a precision reference, switching frequency synchronization, and low side LED current sense. 4 N-Channel Controller for Dimmable LED Drives with Low-Side Current Sense Copyright © 2012, Texas Instruments Incorporated SLVU803 – December 2012 Submit Documentation Feedback Chapter 2 SLVU803 – December 2012 Detailed Description 2.1 Description The TPS92690EVM provides a high-brightness LED driver based on the TPS92690 configured as a boost (step-up) regulator. It is designed to operate with an input voltage in the range of 8 V to 19 V with a 12-V nominal input voltage. This input voltage range is typical for automotive applications and common for many off the shelf AC-DC sources. The EVM is set up for a default output current of 500 mA with an output voltage range of 20 V to 35 V or approximately 7 to 10 LEDs, depending on the forward voltage of each. 2.1.1 Typical Applications This converter design describes an application of the TPS92690 as an LED driver with the specifications listed below. For applications with a different input voltage range or different output voltage range, refer to the TPS92690 datasheet. 2.1.2 Features 2.1.2.1 Connector Description This section describes the connectors and test points on the EVM and how to properly connect, setup, and use the TPS92690EVM. 2.1.2.1.1 J1, J4, J10 (VIN, GND) These two test points and the screw down connector are for the input voltage supply to the converter. The leads to the input supply should be twisted and kept as short as possible to minimize voltage drop, inductance, and EMI transmission. Additional bulk capacitance between VIN and GND may be desirable if the supply leads are greater than twelve inches, particularly if pulse width modulation (PWM) dimming will be used. If using the screw down connector J1, pin 1 is VIN and pin 2 is GND. 2.1.2.1.2 J2, J3, J8 (LED+, LED-) Connect the LED string between J3 and J8 with the anode of one end connected to LED+ and the cathode of the other end connected to LED-. Alternatively, the screw down connector J2 may be used. Pin 1 of J2 is LED- and pin 2 is LED+. 2.1.2.1.3 GND An additional ground test point is provided for ease of use. Ground leads for voltage probes, function generators, or low power analog supplies may be connected to either GND test point. 2.1.2.1.4 PWM DIM This test point is connected through a blocking diode to the nDIM pin of the TPS92690. Pulling this test point to ground will disable switching and turn the LEDs off. A square wave with a low level of ground and a high level greater than the nDIM pin threshold (greater than 1.24 V and up to 30 V) may be applied to this test point to dim using PWM. The average LED current is approximately equal to the positive duty cycle of the PWM signal multiplied by the steady state LED current. The PWM dimming frequency should be between 120 Hz and 1 kHz to maintain the best linearity. SLVU803 – December 2012 Submit Documentation Feedback Detailed Description Copyright © 2012, Texas Instruments Incorporated 5 Description www.ti.com 2.1.2.1.5 SYNC This test point connects directly to the SYNC pin of the TPS92690. Applying a square wave to this test point with a low level of ground and a high level between 2.5 V and 5 V synchronizes the switching frequency of the TPS92690 with the applied square wave. The falling edge of the applied square wave triggers an on time of the power FET. The synchronizing frequency should be at least 10% higher than the native switching frequency set by the resistor from the RT pin to ground. 2.1.2.1.6 SS/SD The SS/SD test point can be used to disable the device and place it into low power shutdown. It may also be used for monitoring the soft-start function with a voltage probe. Pull this test point to ground to disable the circuit. 2.1.2.1.7 IADJ The IADJ test point is connected directly to the IADJ pin of the TPS92690. A resistor divider from VREF sets the default level of the IADJ pin to 500 mV which results in a default LED current of 500 mA. A low power voltage supply can be connected to the IADJ test point to either increase or decrease the LED current. This provides the analog dimming functionality of the TPS92690. 2.1.2.1.8 SW This test point is strictly for monitoring the switching waveform. It is connected directly to the drain of the power switching FET. 6 Detailed Description SLVU803 – December 2012 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Chapter 3 SLVU803 – December 2012 Electrical Performance Specifications Table 3-1. TPS92690EVM Electrical Performance Specifications PARAMETER TEST CONDITIONS MIN TYP MAX 12 19 UNITS Input Characteristics Voltage range Maximum input current Undervoltage lockout level 8 V At IOUT = 500 mA 2.4 A Input rising 7.8 V Input falling 5.5 V Output Characteristics Output voltage, VOUT At IOUT = 500 mA 20 35 Output load current, IOUT IADJ = 0 V to 1 V 2 Output current regulation Line Regulation: Input voltage = 8 V to 19 V 0.5 % Output current ripple At IOUT = 500 mA 25 mApp Overvoltage protection level Output rising 500 1000 V mA 41.3 V 420 kHz Systems Characteristics Switching frequency Efficiency Input voltage = 12 V, Load = 10 LEDs at 500 mA PWM Dim frequency 94 120 SLVU803 – December 2012 Submit Documentation Feedback % 1000 Electrical Performance Specifications Copyright © 2012, Texas Instruments Incorporated Hz 7 Chapter 4 SLVU803 – December 2012 Schematic µF µF µF µF Figure 4-1. TPS92690EVM Schematic 8 Schematic SLVU803 – December 2012 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated Chapter 5 SLVU803 – December 2012 Performance Data and Typical Characteristic Curves Figure 5-1 through Figure 5-8 show typical performance curves for the TPS92690EVM. 5.1 Efficiency 100 Efficiency (%) 98 96 94 92 10 LEDs @ 500mA 90 10 12 14 Input Voltage (V) 16 18 G000 Figure 5-1. Efficiency 5.2 Line Regulation 510 Output Current (mA) 506 502 498 494 10 LEDs 490 8 10 12 14 Input Voltage (V) 16 18 G001 Figure 5-2. Line Regulation SLVU803 – December 2012 Submit Documentation Feedback Performance Data and Typical Characteristic Curves Copyright © 2012, Texas Instruments Incorporated 9 Switch Node Voltage and LED Current Ripple 5.3 www.ti.com Switch Node Voltage and LED Current Ripple Switching Node LED Current Figure 5-3. Switching and LED Current 5.4 PWM Dimming PWM DIM Switching Node LED Current Figure 5-4. PWM Dimming, fPWM = 200 Hz, Duty Cycle = 50% PWM DIM Switching Node LED Current Figure 5-5. PWM Dimming, fPWM = 200 Hz, Duty Cycle = 5% 10 Performance Data and Typical Characteristic Curves Copyright © 2012, Texas Instruments Incorporated SLVU803 – December 2012 Submit Documentation Feedback Start-up and Shut-down Response www.ti.com PWM DIM Switching Node LED Current Figure 5-6. PWM Dimming, fPWM = 200 Hz, Duty Cycle = 95% 5.5 Start-up and Shut-down Response SS/SD Switching Node LED Current Figure 5-7. Start-up Waveform SS/SD Switching Node LED Current Figure 5-8. Shut-down Waveform SLVU803 – December 2012 Submit Documentation Feedback Performance Data and Typical Characteristic Curves Copyright © 2012, Texas Instruments Incorporated 11 Thermal Performance 5.6 www.ti.com Thermal Performance Figure 5-9 and Figure 5-10 show the steady state thermal performance of the EVM under the following conditions: • Load of 10 LEDs • ILED = 500 mA • VIN = 12 VDC Figure 5-9. Top Thermal Performance Figure 5-10. Bottom Thermal Performance 12 Performance Data and Typical Characteristic Curves Copyright © 2012, Texas Instruments Incorporated SLVU803 – December 2012 Submit Documentation Feedback Chapter 6 SLVU803 – December 2012 TPS92690EVM PCB layout Figure 6-1 and Figure 6-2 show the design of the TPS92690EVM printed circuit board. Figure 6-1. Top Layer and Top Overlay (Top View) Figure 6-2. Bottom Layer and Bottom Overlay (Bottom View) SLVU803 – December 2012 Submit Documentation Feedback TPS92690EVM PCB layout Copyright © 2012, Texas Instruments Incorporated 13 Appendix A SLVU803 – December 2012 Bill of Materials Table A-1. The TPS92690EVM Components List (According to the Schematic Shown in Figure 4-1) REFERENCE DESIGNATOR 14 QTY VALUE DESCRIPTION DC-DC Controller with Low Side FET and Low Side Current Sense SIZE MFR eTSSOP-16 TI PART NUMBER U1 1 C3 1 0.1 µF Capacitor, Ceramic, 100 V, X7R 0805 Kemet C5, C6 2 4.7 µF Capacitor, Ceramic, 50 V, X7R 2220 MuRata GRM55ER71H475MA01L C7, C8 2 4.7 µF Capacitor, Ceramic, 50 V, X7R 1210 MuRata GRM32ER71H475KA88L C9 1 2.2 µF Capacitor, Ceramic, 16 V, X7R 0805 MuRata GRM21BR71C225KA12L C10, C11 2 2.2 µF Capacitor, Ceramic, 50 V, X7R 1812 TDK C4532X7R1H225M C12 1 0.047 µF Capacitor, Ceramic, 50 V, X8R 0603 TDK C1608X8R1H473K C13, C15, C17 3 0.1 µF Capacitor, Ceramic, 50 V, X7R 0805 MuRata GRM21BR71H104KA01L C14 1 0.1 µF Capacitor, Ceramic, 25 V, X7R 0603 MuRata GRM188R71E104KA01D C16 1 1000 pF Capacitor, Ceramic, 50 V, X7R 0805 Kemet D1 1 Diode, Schottky, 30 V, 0. 2 A SOD-123 ON Semi MMSD301T1G D2 1 Diode, Schottky, 60 V, 2 A SMB ON Semi SS26T3G L1 1 12 mm x 12 mm Coilcraft MSS1278-223MLD Q7 1 D-PAK Fairchild FDD3682 R1 1 53.6 kΩ Resistor, Chip, 1/8 W, 1% 0805 Std Std R2, R4 2 10 kΩ Resistor, Chip, 1/8 W, 1% 0805 Std Std R3 1 56.2 kΩ Resistor, Chip, 1/8 W, 1% 0805 Std Std R5, R8, R9 3 100 kΩ Resistor, Chip, 1/8 W, 1% 0805 Std Std R6 1 0.1 Ω Resistor, Chip, 1/2 W, 1% 2010 Dale WSL2010R1000FEA R7 1 26.1 kΩ Resistor, Chip, 1/8 W, 1% 0805 Std Std R10 1 909 kΩ Resistor, Chip, 1/8 W, 1% 0805 Std Std R11, R17 2 0Ω Resistor, Chip, 1/8 W, 1% 0805 Std Std R12 1 1.74 kΩ Resistor, Chip, 1/8 W, 1% 0805 Std Std R13 1 1 kΩ Resistor, Chip, 1/8 W, 1% 0805 Std Std R14 1 47 Ω Resistor, Chip, 1/10 W, 5% 0603 Std Std R16 1 0Ω Resistor, Chip, 1/10 W, 5% 0603 Std Std R19 1 0Ω Resistor, Chip, 1 W, 1% 2512 Dale CRCW25120000Z0EG R21 1 10 kΩ Resistor, Chip, 1/10 W, 5% 0603 Std Std C1 0 DNP C4 0 DNP R15 0 DNP R18 0 DNP R20 0 DNP 22 µH Inductor, SMT, 6 A MOSFET, N-channel, 100 V, 32 A Bill of Materials TPS92690PWP C0805C104K1RACTU C0805C102K5RACTU SLVU803 – December 2012 Submit Documentation Feedback Copyright © 2012, Texas Instruments Incorporated IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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